York Ostermeyer

Multidimensional Pareto optimization as an approach for site-specific building refurbishment solutions applicable for life cycle sustainability assessment

PurposeThis paper addresses the application and potential of LCSA in the built environment with a focus on refurbishments of residential buildings. It specifically addresses the phenomenon of interchange of building technologies efficiencies under different life time assessments from economy, ecology and social fields. An approach of optimization rather than hard target numbers is proposed as win–win–win situations are unlikely.MethodsA multidimensional Pareto optimization methodology, using LCC, LCA combined with first stages of a social assessment in a feasibility study but potentially later full SLCA, is proposed, which site-specifically visualizes the interchange between different options in building design or modification, and evaluates optimal overall concepts. LCA and LCC are used to analyze a case study from an EU project named BEEM-UP in which solutions for large-scale uptake of refurbishment strategies are developed. Social frame conditions are taken into account by identifying the driving technologies and feeding the consequences of their implementation for the residents into the tenant involvement part of the project.Results and discussionThe calculations prove that the general assumptions leading to the methodology hold true at least for this case study. A clear Pareto-optimal curve is visible when assessing LCC and LCA. The example buildings results show certain systems to be dominating clusters on the figures while others clearly can be identified as not relevant. Several of the driving technologies however fail to be applicable because of social frame conditions, e.g., clear requests by the tenants. Based on the conclusions, the potential for including SLCA as a third dimension in the methodology and possible visualization options are discussed.ConclusionsThe development in the field of social indicators in the building sector has to be strengthened in order to come up with a holistic picture and respectively with appropriate responses to current challenges. While some solutions identified in the LCC/LCA assessment also have good social characteristics, several others have not and solutions identified as lacking might have social advantages that are currently left out of consideration The upcoming Standards EN 15643-5 and ISO 15686-x are a promising step in this direction as is the work to create a conceptual framework for impact assessment within SLCA by the scientific community.

Environmental Impact of Buildings—What Matters?

The goal of this study was to identify drivers of environmental impact and quantify their influence on the environmental performance of wooden and massive residential and office buildings. We performed a life cycle assessment and used thermal simulation to quantify operational energy demand and to account for differences in thermal inertia of building mass. Twenty-eight input parameters, affecting operation, design, material, and exogenic building properties were sampled in a Monte Carlo analysis. To determine sensitivity, we calculated the correlation between each parameter and the resulting life cycle inventory and impact assessment scores. Parameters affecting operational energy demand and energy conversion are the most influential for the buildings total environmental performance. For climate change, electricity mix, ventilation rate, heating system, and construction material rank the highest. Thermal inertia results in an average 2-6% difference in heat demand. Nonrenewable cumulative energy demand of wooden buildings is 18% lower, compared to a massive variant. Total cumulative energy demand is comparable. The median climate change impact is 25% lower, including end-of-life material credits and 22% lower, when credits are excluded. The findings are valid for small offices and residential buildings in Switzerland and regions with similar building culture, construction material production, and climate.

Factors for Eco-Efficiency Improvement of Thermal Insulation Materials

Thermal insulation material is an important component to reduce the environmental impact of buildings through the reduction of energy consumption in the operation phase. However, the material itself has embodied environmental impacts for the value it provides. Eco-efficiency is a method that quantifies relation between the environmental performance and the created value of a product system. This study investigated contributing factors of the eco-efficiency of thermal insulation materials to support decision making of material manufacturers. For the improvement of eco-efficiency, the assessment was made in two scopes: investigating the contributing factors of impact caused at production processes; and thermal performance through thermo-physical properties. For quantifying environmental impacts, cradle-to-grave life cycle assessment (LCA) of each materials were made. The life cycle impact assessment (LCIA) indicators used were ReCiPe H/A and global warming potential (GWP100a). For the assessment of production process, the inventories of the materials were assigned to six categories: heat, chemicals, electricity, transportation, raw materials and wastes. Among the assessed materials, contribution of electricity and heat within the production process was large for foam glass which had the highest potential to improve the eco-efficiency which was by factor 1.72. The analysis on relation between thermo-physical properties and eco-efficiency based on product data of the materials highlighted the importance of density as an indicator upon development and use. Althoughdensity often gains less attention,the finding suggested the effectiveness of improving the efficiency by having lower density without compensating the performance of the materials.

The trends of hourly carbon emission factors in Germany and investigation on relevant consumption patterns for its application

PurposeThe share of variable renewable energy sources (vRES) in the German electricity grid has increased over the past few decades. Due to the nature of the generation pattern of vRES, the increase of vRES causes the emission factor (EF) to fluctuate on an hourly basis. This fluctuation raises concerns about the accuracy of quantifying emissions with the current metric of the annual average EF as the respective EF may change depending on the time at which it is consumed.MethodsThe study calculated the hourly EF of Germany from 2011 to 2015 and investigated the effect of an increase of vRES on the EF. The calculated hourly EF was clustered based on three aspects of time: the period of time, the time of a day, and the day of the week.Results and discussionThe study showed a higher proportion of vRES on weekend daytimes while the weekday nighttimes resulted in a lower share than the annual average. The study highlighted potential underestimation and overestimation of emissions by using annual average EF which ranged from +22% (2015 weekday nighttime of October) to −34% (2015 weekend daytime of May).ConclusionsThe study suggested that the application of hourly EF may be necessary to quantify the respective emission from the consumers that use electricity during the weekend daytime and weekend nighttime. For consumer use at other times, the emissions could be quantified appropriately by using the conventional annual average EF.